Multilayer coil component

Abstract

A stacked coil component 1 comprises: a stacked body 10 in which a plurality of insulation layers 41-45 are stacked; a coil 20 constituted by a plurality of coil conductors 51-54 that are stacked together with the insulation layers 41-45 and embedded in the stacked body 10, and that are electrically connected; and an external electrode 30 that is provided on the outer surface of the stacked body 10 and electrically connected to the coil 20. At least a portion of the interface between the insulation layers 41-45 and the coil conductors 51-54 is provided with an inorganic material layer 70, which includes a porous material 75 made of an inorganic material.

Description

Technical Field

[0001] The present invention relates to a multilayer coil component.

Background Art

[0002] Patent Document 1 discloses an electronic component including a base body and a coil provided inside the base body, wherein the base body has a sintered first portion and a second portion located within the first portion and made of unsintered powder, and the coil is disposed within the second portion and covered with the powder constituting the second portion.

[0003] Patent Document 2 discloses a multilayer coil component including a base body containing a magnetic material, a coil including a plurality of internal conductors spaced apart from each other in a first direction and electrically connected to each other within the base body, and a plurality of stress relaxation spaces in contact with the surfaces of the internal conductors and in which powder exists. The base body has a base body region located between the internal conductors adjacent to each other in the first direction, each stress relaxation space has a first boundary surface with each internal conductor and a second boundary surface with the base body region, the first boundary surface and the second boundary surface face each other in the first direction, and the distance from the first boundary surface to the second boundary surface is smaller than the thickness of the base body region in the first direction.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] According to Patent Document 1, since the coil is arranged in the second part made of unsintered powder, the internal stress generated in the element body can be relaxed by the powder constituting the second part, and it is said that the generation of cracks can be suppressed. However, since the second part is composed of powder, there is a problem that the strength of the element body decreases.

[0006] According to Patent Document 2, since each stress relaxation space where the powder exists is in contact with the surface of each internal conductor and each stress relaxation space is interposed between each internal conductor and the element body region, the internal stress generated in the element body can be relaxed, and it is said that the generation of cracks can be suppressed. However, since the stress relaxation space is composed of powder, there is a problem that the strength of the element body decreases as in Patent Document 1.

[0007] The present invention has been made to solve the above problems, and an object thereof is to provide a laminated coil component having a stress relaxation effect and high strength.

Means for Solving the Problems

[0008] The laminated coil component of the present invention includes a laminate in which a plurality of insulating layers are laminated, a coil formed by electrically connecting a plurality of coil conductors laminated together with the insulating layers and embedded in the laminate, and an external electrode provided on the outer surface of the laminate and electrically connected to the coil. An inorganic material layer is provided on at least a part of the interface between the insulating layer and the coil conductor, and the inorganic material layer includes a porous body made of an inorganic material.

Effects of the Invention

[0009] According to the present invention, a stress relaxation effect can be obtained, and a laminated coil component having high strength can be provided.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0011] Hereinafter, the multilayer coil component of the present invention will be described. However, the present invention is not limited to the following configurations, and can be appropriately changed and applied within the scope that does not change the gist of the present invention. In addition, a combination of two or more of the individual desirable configurations of the present invention described below is also the present invention.

[0012] Figure 1 is a perspective view schematically showing an example of the multilayer coil component of the present invention. Figure 2 is a cross-sectional view taken along line II-II of the multilayer coil component shown in Figure 1. Note that the shapes and arrangements of the multilayer coil component and each component are not limited to the illustrated examples.

[0013] The multilayer coil component 1 shown in Figures 1 and 2 includes a laminate 10, a coil 20, and external electrodes 30.

[0014] The laminate 10 has, for example, a substantially rectangular parallelepiped shape having six faces. It is preferable that the laminate 10 has rounded corners and edges. A corner is a portion where three faces of the laminate 10 intersect, and an edge is a portion where two faces of the laminate 10 intersect.

[0015] In Figures 1 and 2, the length direction, width direction, and height direction of the multilayer coil component 1 and the laminate 10 are shown as the L direction, W direction, and T direction, respectively. The length direction L, width direction W, and height direction T are perpendicular to each other. The mounting surface of the multilayer coil component 1 is, for example, a surface (LW surface) parallel to the length direction L and the width direction W.

[0016] The laminate 10 shown in FIGS. 1 and 2 has a first end face 11 and a second end face 12 that face each other in the length direction L, a first main face 13 and a second main face 14 that face each other in the height direction T orthogonal to the length direction L, and a first side face 15 and a second side face 16 that face each other in the width direction W orthogonal to the length direction L and the height direction T.

[0017] The laminate 10 is configured by laminating a plurality of insulating layers (in the example shown in FIG. 2, insulating layers 41, 42, 43, 44, and 45). In the example shown in FIG. 2, the insulating layers 41, 42, 43, 44, and 45 are laminated along the height direction T. The number of insulating layers to be laminated is not particularly limited as long as it is two or more.

[0018] The coil 20 is configured by electrically connecting a plurality of coil conductors (in the example shown in FIG. 2, coil conductors 51, 52, 53, and 54) embedded in the laminate 10. In the example shown in FIG. 2, the coil conductors 51, 52, 53, and 54 are laminated together with the insulating layers 41, 42, 43, 44, and 45. Therefore, the coil axis of the coil 20 is along the height direction T.

[0019] In the example shown in FIG. 2, the coil conductor 51 and the coil conductor 52 are connected via a via conductor 61, the coil conductor 52 and the coil conductor 53 are connected via a via conductor 62, and the coil conductor 53 and the coil conductor 54 are connected via a via conductor 63.

[0020] The external electrode 30 is provided on the outer surface of the laminate 10 and is electrically connected to the coil 20. The external electrode 30 includes, for example, a first external electrode 31 and a second external electrode 32.

[0021] The first external electrode 31 covers, for example, as shown in FIG. 1, the first end face 11 of the laminate 10, extends from the first end face 11, and covers a part of the first main face 13, a part of the second main face 14, a part of the first side face 15, and a part of the second side face 16. Further, the second external electrode 32 covers, for example, as shown in FIG. 1, the second end face 12 of the laminate 10, extends from the second end face 12, and covers a part of the first main face 13, a part of the second main face 14, a part of the first side face 15, and a part of the second side face 16. In this case, the second main face 14 can be used as the mounting surface.

[0022] Although not shown in FIGS. 1 and 2, for example, the coil conductor 51 constituting the coil 20 is drawn out to the first end face 11 of the laminate 10, and the coil conductor 54 constituting the coil 20 is drawn out to the second end face 12 of the laminate 10. As a result, it is preferable that the first external electrode 31 is electrically connected to the coil conductor 51 at the first end face 11, and it is preferable that the second external electrode 32 is electrically connected to the coil conductor 54 at the second end face 12.

[0023] By changing the position where the coil conductor 51 or 54 is drawn out to the outside of the laminate 10, the connection position between the coil 20 and the external electrode 30 can be changed. That is, the coil 20 and the external electrode 30 may be electrically connected at the end face of the laminate 10, or may be electrically connected at the main face or side face of the laminate 10.

[0024] As shown in FIG. 2, an inorganic material layer 70 is provided on at least a part of the interface between the insulating layer and the coil conductor. In the example shown in FIG. 2, the inorganic material layer 70 is provided at each of the interfaces between the insulating layer 41 and the coil conductor 51, between the insulating layer 42 and the coil conductor 52, between the insulating layer 43 and the coil conductor 53, and between the insulating layer 44 and the coil conductor 54, but the inorganic material layer 70 may be provided at at least one interface. The inorganic material layer 70 may be provided over the entire interface, or may be provided on a part of each interface.

[0025] Although not shown in Fig. 2, an inorganic material layer 70 may be provided on at least a part of the interface between the insulating layer 42 and the coil conductor 51, the interface between the insulating layer 43 and the coil conductor 52, the interface between the insulating layer 44 and the coil conductor 53, and the interface between the insulating layer 45 and the coil conductor 54. In that case, the inorganic material layer 70 may be provided on at least one interface. The inorganic material layer 70 may be provided over the entire interface or on a part of each interface.

[0026] Fig. 3 is a cross-sectional view schematically showing an example of the inorganic material layer.

[0027] As shown in Fig. 3, the inorganic material layer 70 includes a porous body 75 made of an inorganic material. The inorganic material layer 70 may include a second region 82 where the porous body 75 does not exist in addition to the first region 81 where the porous body 75 exists. The second region 82 where the porous body 75 does not exist in the inorganic material layer 70 is preferably a cavity.

[0028] By providing the inorganic material layer 70 between the insulating layer and the coil conductor (for example, between the insulating layer 41 and the coil conductor 51), the stress generated in the laminate 10 due to the difference in the thermal shrinkage rate between the insulating layer and the coil conductor can be relaxed.

[0029] Since the inorganic material layer 70 includes the porous body 75 made of an inorganic material, the strength of the laminate 10 can be increased as compared with the case where a stress relaxation portion made of powder as described in Patent Documents 1 and 2 is provided.

[0030] The thickness of the inorganic material layer 70 is preferably smaller than the thickness of the coil conductor such as the coil conductor 51. When the inorganic material layer 70 is provided on a plurality of interfaces, the thicknesses of the inorganic material layers 70 may be the same or different from each other.

[0031] For example, the thickness of the inorganic material layer 70 may be greater than 0 μm and 1.5 μm or less. When the thickness of the inorganic material layer 70 is 1.5 μm or less, the resistance is reduced, and the coil characteristics are improved by the relative increase in the volume of the laminate. When the inorganic material layer 70 is provided at a plurality of interfaces, if the thickness of any one of the inorganic material layers 70 is greater than 0 μm and 1.5 μm or less, it can be said that the thickness of the inorganic material layer 70 is greater than 0 μm and 1.5 μm or less. It is more preferable that the thickness of all the inorganic material layers 70 is greater than 0 μm and 1.5 μm or less.

[0032] When the thickness of the inorganic material layer 70 is greater than 0 μm and 1.5 μm or less, the thickness of the inorganic material layer 70 is preferably 25% or more with respect to the thickness of the coil conductor. In this case, the thickness of the coil conductor is 6.0 μm or less. When the thickness of the coil conductor is relatively small in this way, if the thickness of the inorganic material layer 70 is 25% or more with respect to the thickness of the coil conductor, a more sufficient stress relaxation effect can be maintained. When the thicknesses of the plurality of coil conductors are not the same, the ratio of the thickness of the inorganic material layer 70 to the thickness of the coil conductor in contact with the interface where the inorganic material layer 70 is provided may be calculated.

[0033] Alternatively, the thickness of the inorganic material layer 70 may be greater than 2 μm. When the thickness of the inorganic material layer 70 is greater than 2 μm, the stress relaxation effect becomes greater. When the inorganic material layer 70 is provided at a plurality of interfaces, if the thickness of any one of the inorganic material layers 70 is greater than 2 μm, it can be said that the thickness of the inorganic material layer 70 is greater than 2 μm. It is more preferable that the thickness of all the inorganic material layers 70 is greater than 2 μm.

[0034] When the thickness of the inorganic material layer 70 is greater than 2 μm, the thickness of the inorganic material layer 70 is preferably 15% or less with respect to the thickness of the coil conductor. In this case, the thickness of the coil conductor is 50 / 3 μm or more. Thus, when the thickness of the coil conductor is relatively large, if the thickness of the inorganic material layer 70 is 15% or less with respect to the thickness of the coil conductor, the volume of the relative laminate can be increased, and the coil characteristics are improved. In addition, when the thicknesses of the plurality of coil conductors are not the same, the ratio of the thickness of the inorganic material layer 70 with respect to the thickness of the coil conductor in contact with the interface where the inorganic material layer 70 is provided may be calculated.

[0035] The thickness of the inorganic material layer 70 and the thickness of the coil conductor refer to the thickness in the direction parallel to the lamination direction passing through the center of the width of the coil conductor when polishing is performed up to the substantially central portion in the width direction W of the laminate 10 and observing a cross section (also referred to as an LT cross section) including the length direction L and the height direction T.

[0036] When viewed from the direction in which the coil conductor such as the coil conductor 51 extends, the width of the inorganic material layer 70 may be the same as the width of the coil conductor or may be smaller than the width of the coil conductor. When the inorganic material layer 70 is provided at a plurality of interfaces, the widths of the inorganic material layers 70 may be the same or different.

[0037] As shown in FIG. 3, the porous body 75 is preferably configured by joining adjacent inorganic material particles by necking.

[0038] In the inorganic material layer 70, the greater the ratio of the first region 81 where the porous body 75 exists, the higher the strength of the laminate 10. Therefore, in the inorganic material layer 70, the ratio of the first region 81 to the total of the first region 81 where the porous body 75 exists and the second region 82 where the porous body 75 does not exist is preferably 50% or more and 100% or less, and more preferably 70% or more and 100% or less. When the ratio of the first region 81 in the inorganic material layer 70 is 100%, the inorganic material layer 70 includes only the first region 81 and does not include the second region 82.

[0039] In addition, in the inorganic material layer 70, when including a second region where the porous body 75 does not exist, the ratio of the first region 81 where the porous body 75 exists to the total of the first region 81 where the porous body 75 exists and the second region 82 where the porous body 75 does not exist may be 15% or more and 50% or less.

[0040] Note that the ratio of the first region 81 and the ratio of the second region 82 in the inorganic material layer 70 can be calculated by performing polishing up to the substantially central portion in the width direction W of the laminate 10 and observing a cross section (also referred to as an LT cross section) including the length direction L and the height direction T, and obtaining the area of the first region 81 where the porous body 75 exists and the area of the second region 82 where the porous body 75 does not exist. At this time, the "area of the first region 81 where the porous body 75 exists" includes not only the area of the inorganic material constituting the porous body 75 but also the area of the void surrounded entirely by the inorganic material constituting the porous body 75.

[0041] The porosity of the inorganic material layer 70 is preferably larger than the porosity of the insulating layer. The porosity of the inorganic material layer 70 can be calculated by performing polishing up to the substantially central portion in the width direction W of the laminate 10 and observing the LT cross section, and obtaining the area of the void portion in the inorganic material layer 70 with respect to the entire area of the inorganic material layer 70 (including the area of the void portion). Similarly, the porosity of the insulating layer can be calculated by performing polishing up to the substantially central portion in the width direction W of the laminate 10 and observing the LT cross section, and obtaining the area of the void portion in the insulating layer with respect to the entire area of the insulating layer (including the area of the void portion).

[0042] As shown in FIG. 3, the porous body 75 is preferably joined to an insulating layer such as the insulating layer 41. Specifically, the porous body 75 is preferably joined to an insulating layer such as the insulating layer 41 via necking. Thereby, the strength of the laminate 10 is further increased.

[0043] As shown in FIG. 3, the porous body 75 is preferably joined to a coil conductor such as the coil conductor 51. Specifically, the porous body 75 is preferably joined to a coil conductor such as the coil conductor 51 via necking. Thereby, the strength of the laminate 10 is further increased.

[0044] Examples of the inorganic material constituting the porous body 75 include oxides, carbides, nitrides, etc. The inorganic material constituting the porous body 75 may be a metal material. Examples of the inorganic material constituting the porous body 75 include magnetic ferrite materials, metal magnetic materials, non-magnetic ferrite materials, glass materials, zirconia, forsterite, steatite, yttria, mullite, cordierite, silicon carbide, silicon nitride, etc. These inorganic materials may be of one kind or two or more kinds.

[0045] As an example, the inorganic material constituting the porous body 75 includes a glass material and one kind of material other than the glass material. Since the glass material makes it easier for the particles of other inorganic materials to neck, the porous body 75 is more easily formed.

[0046] As one kind of material other than the glass material, for example, zirconia or the like can be used.

[0047] The melting point of the glass material is preferably lower than the melting point of one kind of material other than the glass material. As the glass material, for example, borosilicate glass containing Si and B as main components, those obtained by adding Na and / or Al to the borosilicate glass, those obtained by adding at least one of Bi, Ba, Sr, Ca, and Zn to these borosilicate glasses, etc. can be used. These glasses may be of one kind or two or more kinds.

[0048] The insulating layer such as the insulating layer 41 is preferably composed of a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu. For example, a magnetic ferrite material in which Fe is 40 mol% or more and 49.5 mol% or less in terms of Fe2O3, Zn is 5 mol% or more and 35 mol% or less in terms of ZnO, Cu is 4 mol% or more and 12 mol% or less in terms of CuO, and the balance is NiO can be preferably used. Trace additives (including inevitable impurities) such as Mn, Co, Sn, Bi, and Si may be contained in the above magnetic ferrite material.

[0049] When the insulating layer such as the insulating layer 41 is composed of the above magnetic ferrite material, the inorganic material constituting the porous body 75 may be a non-magnetic ferrite material or a magnetic ferrite material having a sintering temperature higher than that of the magnetic ferrite material constituting the insulating layer.

[0050] When the inorganic material constituting the porous body 75 is a non-magnetic ferrite material, for example, a non-magnetic ferrite material in which Fe is 40 mol% or more and 49.5 mol% or less in terms of Fe2O3, Cu is 4 mol% or more and 12 mol% or less in terms of CuO, and the balance is ZnO can be preferably used. Trace additives (including inevitable impurities) such as Mn, Co, Sn, Bi, and Si may be contained in the above non-magnetic ferrite material. By increasing the calcination temperature of the non-magnetic ferrite material or adjusting the pulverized particle size of the calcined product of the non-magnetic ferrite material with respect to the magnetic ferrite material constituting the insulating layer, the sintering temperature becomes higher than that of the magnetic ferrite material constituting the insulating layer, so that the porous body 75 can be easily formed.

[0051] When the inorganic material constituting the porous body 75 is a magnetic ferrite material, for example, a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu and having a higher Ni content than the magnetic ferrite material constituting the insulating layer can be used. By increasing the Ni content, the sintering temperature becomes higher than that of the magnetic ferrite material constituting the insulating layer, so that the porous body 75 can be easily formed.

[0052] When the inorganic material constituting the porous body 75 is a magnetic ferrite material, for example, a magnetic ferrite material having a higher calcination temperature than the magnetic ferrite material constituting the insulating layer may be used. In this case, the magnetic ferrite material constituting the porous body 75 may have the same composition as the magnetic ferrite material constituting the insulating layer, or may have a different composition. Regardless of the Ni content, by increasing the calcination temperature, the sintering temperature becomes higher than that of the magnetic ferrite material constituting the insulating layer, so that the porous body 75 can be easily formed.

[0053] Also, when the inorganic material constituting the porous body 75 is a magnetic ferrite material, for example, by adjusting the pulverized particle size of the calcined product of the magnetic ferrite material, the sintering temperature becomes higher than that of the magnetic ferrite material constituting the insulating layer, so that the porous body 75 can be easily formed.

[0054] Regarding the inorganic material such as the ferrite material constituting the porous body 75, the temperature at which the shrinkage of the shrinkage curve becomes substantially parallel to the horizontal axis is defined as the sintering temperature by thermomechanical analysis (TMA).

[0055] Hereinafter, an example of a method for manufacturing the laminated coil component of the present invention will be described.

[0056] For example, a ferrite sheet, a ferrite paste, an inorganic material paste, and a conductor paste are prepared as materials.

[0057] As the material of the ferrite sheet, it is preferable to use a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu. As the magnetic ferrite material, a magnetic ferrite material in which Fe is 40 mol% or more and 49.5 mol% or less in terms of Fe2O3, Zn is 5 mol% or more and 35 mol% or less in terms of ZnO, Cu is 4 mol% or more and 12 mol% or less in terms of CuO, and the balance is NiO can be preferably used. Trace additives (including inevitable impurities) such as Mn, Co, Sn, Bi, and Si may be contained in the above magnetic ferrite material.

[0058] Examples of the method for producing a ferrite sheet include the following methods. Weigh Fe2O3, ZnO, CuO, NiO, and additives as necessary so that they have a predetermined composition. Put the weighed materials into a ball mill together with pure water, a dispersant, and PSZ (partially stabilized zirconia) media, and mix and grind them. After drying the obtained slurry, calcine it under the conditions of a temperature of 700 °C or higher and 800 °C or lower, and a time of 2 hours or longer and 3 hours or shorter. Put the calcined powder of the obtained ferrite material, an organic binder such as polyvinyl butyral, and an organic solvent such as ethanol and toluene into a ball mill together with PSZ media, and mix and grind them. After shaping the obtained mixture into a sheet of a predetermined thickness by the doctor blade method, punch it into a predetermined size to produce a ferrite sheet.

[0059] As the material of the ferrite paste, it is preferable to use a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu. As the magnetic ferrite material, a magnetic ferrite material in which Fe is 40 mol% or more and 49.5 mol% or less in terms of Fe2O3, Zn is 5 mol% or more and 35 mol% or less in terms of ZnO, Cu is 4 mol% or more and 12 mol% or less in terms of CuO, and the balance is NiO can be preferably used. The above magnetic ferrite material may contain trace additives (including unavoidable impurities) such as Mn, Co, Sn, Bi, and Si.

[0060] Examples of the method for producing a ferrite paste include the following methods. Put a predetermined amount of a solvent (such as a ketone-based solvent), a resin (such as polyvinyl acetal), and a plasticizer (such as an alkyd-based plasticizer) into the calcined powder of the ferrite material obtained by the above method for producing a ferrite sheet, knead it with a planetary mixer, and then disperse it with a three-roll mill to produce a ferrite paste.

[0061] As the material of the inorganic material paste, it is preferable to use inorganic materials such as magnetic ferrite materials, metallic magnetic materials, non-magnetic ferrite materials, glass materials, zirconia, forsterite, steatite, yttria, mullite, cordierite, silicon carbide, and silicon nitride. These inorganic materials may be used alone or in combination of two or more.

[0062] As an example, the inorganic material paste contains a glass material and one material other than the glass material. As the one material other than the glass material, for example, zirconia or the like can be used. The melting point of the glass material is preferably lower than the melting point of the one material other than the glass material.

[0063] When a magnetic ferrite material is used as the material of the ferrite sheet and the ferrite paste, a non-magnetic ferrite material may be used as the material of the inorganic material paste, or a magnetic ferrite material having a sintering temperature higher than that of the magnetic ferrite material of the ferrite sheet and the ferrite paste may be used.

[0064] Examples of the method for producing the inorganic material paste include the following methods. A predetermined amount of a solvent (such as a ketone-based solvent), a resin (such as polyvinyl acetal), etc. is added to the powder of the inorganic material, kneaded with a planetary mixer, and then dispersed with a three-roll mill to produce an inorganic material paste.

[0065] As the conductor paste, it is preferable to use a paste containing silver as the conductive material.

[0066] Examples of the method for producing the conductor paste include the following methods. Silver powder is prepared, a predetermined amount of a solvent (such as eugenol), a resin (such as ethyl cellulose), and a dispersant are added, kneaded with a planetary mixer, and then dispersed with a three-roll mill to produce a conductor paste.

[0067] Next, using the above materials, a laminate 10 incorporating a coil 20 is produced.

[0068] Figures 4A1 to 4A4, Figures 4B1 to 4B4, Figures 4C1 to 4C4, and Figures 4D1 to 4D4 are exploded views schematically showing an example of a method for manufacturing a laminate in which a coil is incorporated.

[0069] First, a ferrite sheet 141 is prepared (Fig. 4A1).

[0070] An inorganic material paste layer 170 is formed by printing an inorganic material paste at a location on the ferrite sheet 141 where the inorganic material layer 70 (see Fig. 2) is to be formed (Fig. 4A2).

[0071] A conductor paste layer 151 is formed by printing a conductor paste at a location where the coil conductor 51 (see Fig. 2) is to be formed (Fig. 4A3). As shown in Fig. 4A3, it is preferable to draw out one end of the conductor paste layer 151 to the end face of the ferrite sheet 141.

[0072] A ferrite paste layer 140 is formed by printing a ferrite paste in a region where the conductor paste layer 151 is not formed (Fig. 4A4).

[0073] By the above steps, a sheet S1 is formed on which an inorganic material paste layer 170, a conductor paste layer 151, and a ferrite paste layer 140 are printed on the ferrite sheet 141.

[0074] Separately, a ferrite sheet 142 is prepared, and a via hole 161 is formed by irradiating a laser at a location where it is to be connected to the conductor paste layer 151 formed on the sheet S1 (Fig. 4B1).

[0075] An inorganic material paste layer 170 is formed by printing an inorganic material paste at a location on the ferrite sheet 142 where the inorganic material layer 70 is to be formed (Fig. 4B2).

[0076] By printing a conductor paste at the location where the coil conductor 52 (see FIG. 2) is formed, the conductor paste layer 152 is formed, and the via hole 161 is filled with the conductor paste (FIG. 4B3).

[0077] By printing a ferrite paste in the region where the conductor paste layer 152 is not formed, the ferrite paste layer 140 is formed (FIG. 4B4).

[0078] Through the above steps, a sheet S2 is formed on the ferrite sheet 142 having the via hole 161, on which the inorganic material paste layer 170, the conductor paste layer 152, and the ferrite paste layer 140 are printed.

[0079] In the same procedure as for the sheet S2, a sheet S3 (FIGS. 4C1 to C4) on which the inorganic material paste layer 170, the conductor paste layer 153, and the ferrite paste layer 140 are printed on the ferrite sheet 143 having the via hole 162, and a sheet S4 (FIGS. 4D1 to D4) on which the inorganic material paste layer 170, the conductor paste layer 154, and the ferrite paste layer 140 are printed on the ferrite sheet 144 having the via hole 163 are produced. As shown in FIG. 4D3, it is preferable to draw out one end of the conductor paste layer 154 to the end face of the ferrite sheet 144.

[0080] The sheets S1, S2, S3, and S4 produced as described above are laminated in a predetermined order, and a predetermined number of ferrite sheets on which no paste layer is printed are stacked on the top and bottom thereof. The stacked sheets are subjected to warm isostatic pressing (WIP) treatment under the conditions of a temperature of 70°C or higher and 90°C or lower and a pressure of 60 MPa or higher and 100 MPa or lower, thereby obtaining a laminate block which is an assembly of elements.

[0081] The laminate block is cut into individual pieces with a dicing machine or the like to obtain elements. The obtained elements are placed in a firing furnace and fired under the conditions of a temperature of 900°C or higher and 920°C or lower for 2 hours or more and 4 hours or less.

[0082] After firing, the ferrite sheet 141 and the ferrite sheet laminated thereunder become the insulating layer 41. The ferrite paste layer 140 printed on the ferrite sheet 141 and the ferrite sheet 142 become the insulating layer 42. The ferrite paste layer 140 printed on the ferrite sheet 142 and the ferrite sheet 143 become the insulating layer 43. The ferrite paste layer 140 printed on the ferrite sheet 143 and the ferrite sheet 144 become the insulating layer 44. The ferrite paste layer 140 printed on the ferrite sheet 144 and the ferrite sheet laminated on the ferrite sheet 144 become the insulating layer 45.

[0083] Also, after firing, the inorganic material paste layer 170 becomes the inorganic material layer 70, the conductor paste layers 151 to 154 become the coil conductors 51 to 54, and the conductor paste filled in the via holes 161 to 163 becomes the via conductors 61 to 63. The coil 20 is formed by the coil conductors 51 to 54 and the via conductors 61 to 63.

[0084] It is preferable to form roundness at the ridge line portions and corner portions of the element by putting the fired element together with a medium into a rotary barrel machine and rotating it. Through the above steps, the laminate 10 incorporating the coil 20 is obtained.

[0085] A conductive paste containing silver and glass is applied to the end face from which the coil 20 is drawn out on the side surface of the laminate 10. By baking the conductive paste under the conditions of a temperature of 800 °C or higher and 820 °C or lower, the base electrode of the external electrode 30 is formed. The thickness of the base electrode is, for example, about 5 μm.

[0086] The external electrode 30 is formed by sequentially forming a Ni film and a Sn film on the base electrode by electrolytic plating.

[0087] Thus, the multilayer coil component 1 as shown in FIG. 1 is obtained. The size of the multilayer coil component 1 is, for example, the dimension in the length direction L is 0.6 mm, the dimension in the width direction W is 0.3 mm, and the dimension in the height direction T is 0.3 mm.

Example

[0088] Hereinafter, examples that more specifically disclose the laminated coil component of the present invention are shown. Note that the present invention is not limited only to these examples.

[0089] (Example 1) Fe2O3, ZnO, NiO, and CuO were blended at a predetermined ratio, mixed and pulverized wet, and then dried to remove moisture. The obtained dried product was calcined at a temperature of 800 ° C for 2 hours to produce a ferrite material which is a magnetic material. A ferrite sheet and a ferrite paste were produced from the obtained magnetic material.

[0090] Zirconia powder was prepared as an inorganic material for forming a porous body of the inorganic material layer. Separately, glass powder having a melting point lower than that of zirconia powder was prepared. An inorganic material paste was produced using a powder of an inorganic material containing a predetermined amount of glass powder in zirconia powder.

[0091] Using the produced ferrite sheet, ferrite paste, inorganic material paste, and Ag paste, a laminated coil component was produced by the procedure described in [Mode for Carrying Out the Invention], and used as a sample of Example 1.

[0092] The produced sample was stood up vertically so that the LT plane was exposed, and the periphery of the sample was solidified with resin. Polishing was performed up to a substantially central portion in the W direction of the sample using a polishing machine. A photograph of the obtained cross section was taken at a magnification of 10,000 times with a scanning electron microscope (SEM). Using image processing software, the area of the first region where the porous body exists and the area of the second region where the porous body does not exist in the inorganic material layer were determined. The area was measured at five locations and the average value was obtained. As a result, the ratio of the first region to the total of the first region and the second region was 85%.

[0093] (Comparative Example 1) A laminated coil component was fabricated in the same manner as in Example 1, except that an inorganic material paste prepared using only zirconia powder without containing glass powder was used instead of the inorganic material paste prepared in Example 1, and the resulting sample was designated as Comparative Example 1.

[0094] In Comparative Example 1, when the sample was polished in the same manner as in Example 1, the loss of zirconia powder from the sample was confirmed. From this result, it is considered that in the sample of Comparative Example 1, the zirconia particles, which are inorganic materials, exist not in a porous state but in a powder state.

[0095] Also, a deflection strength test was performed on the samples of Example 1 and Comparative Example 1. As a result, it was confirmed that the deflection strength of the sample of Example 1 was higher than that of the sample of Comparative Example 1. Also, 100 samples of the sample of Example 1 were fabricated, polished up to approximately the central portion in the width direction W of the laminate 10, and the LT cross-section was observed. As a result, it was confirmed that no cracks occurred and the internal stress was relieved.

Explanation of Signs

[0096] 1 Laminated coil component 10 Laminate 11 First end face 12 Second end face 13 First main face 14 Second main face 15 First side face 16 Second side face 20 Coil 30 External electrode 31 First external electrode 32 Second external electrode 41, 42, 43, 44, 45 Insulation layer 51, 52, 53, 54 Coil conductor 61, 62, 63 Via conductor 70 Inorganic material layer 75 Porous body 81 First region where porous body exists 82 Second region where porous body does not exist 140 Ferrite paste layer 141, 142, 143, 144 Ferrite sheets 151, 152, 153, 154 Conductor paste layers 161, 162, 163 Via holes 170 Inorganic material paste layer S1, S2, S3, S4 Sheets L Length direction T Height direction W Width direction

Claims

1. A laminate in which a plurality of insulating layers are laminated, A coil formed by electrically connecting a plurality of coil conductors laminated together with the insulating layer and embedded in the laminate, An external electrode provided on the outer surface of the laminate and electrically connected to the coil, An inorganic material layer is provided on at least a part of the interface between the insulating layer and the coil conductor, The inorganic material layer includes a porous body made of an inorganic material containing a glass material, The porous body is formed by joining adjacent inorganic material particles by necking, a laminated coil component.

2. The laminated coil component according to claim 1, wherein the thickness of the inorganic material layer is greater than 0 μm and 1.5 μm or less.

3. The laminated coil component according to claim 2, wherein the thickness of the inorganic material layer is 25% or more with respect to the thickness of the coil conductor.

4. The laminated coil component according to claim 1, wherein the thickness of the inorganic material layer is greater than 2 μm.

5. The laminated coil component according to claim 4, wherein the thickness of the inorganic material layer is 15% or less with respect to the thickness of the coil conductor.

6. The laminated coil component according to claim 1, wherein the ratio of the first region where the porous body exists to the total of the first region where the porous body exists and the second region where the porous body does not exist in the inorganic material layer is 50% or more and 100% or less.

7. The laminated coil component according to claim 1, wherein the ratio of the first region where the porous body exists to the total of the first region where the porous body exists and the second region where the porous body does not exist in the inorganic material layer is 15% or more and 50% or less.

8. The laminated coil component according to claim 1, wherein the porosity in the inorganic material layer is greater than the porosity in the insulating layer.

9. The laminated coil component according to claim 1, wherein the porous body is joined to the insulating layer.

10. The laminated coil component according to claim 1, wherein the porous body is joined to the coil conductor.

11. The laminated coil component according to claim 1, wherein the inorganic material contains at least one selected from the group consisting of a magnetic ferrite material, a metallic magnetic material, a non-magnetic ferrite material, a glass material, zirconia, forsterite, steatite, yttria, mullite, cordierite, silicon carbide, and silicon nitride.

12. The laminated coil component according to claim 1, wherein the inorganic material contains a glass material and one material other than the glass material.

13. The laminated coil component according to claim 12, wherein the one material other than the glass material is zirconia.

14. The laminated coil component according to claim 1, wherein the insulating layer is composed of a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu.

15. The laminated coil component according to claim 14, wherein the inorganic material is a magnetic ferrite material containing at least Fe, Ni, Zn, and Cu and having a higher Ni content than the magnetic ferrite material constituting the insulating layer.

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